The present invention relates to a disc recording method and an apparatus using the method.
In the conventional disc device, a position where recording starts is fixed to a point in a basic recording area such as a sector prescribed according to disc standards, and neither recording nor a start of recording at any position in any one of unit subareas of the basic recording area has been considered.
Thus, when recording cannot help stopping at an unexpected position in any basic recording area due to some external cause such as buffer under-run/vibrations or shocks during recording in a disc-type recording medium such as especially a DVD-R or DVD-RW that basically employs sequential recording, the disc must be exchanged with another or re-recording must be performed, in order to cope with such accident.
For example, when the disc device stops its recording at an unexpected position due to some external cause during Disc-at-Once recording on a write once-type DVD-R, this disc must be discarded and re-recording must be made on a new disc from the beginning. When recording stops at an unexpected position in a rewritable DVD-RW, data recorded before the stoppage of the disc must be erased from the disc and re-recorded on the disc.
The Disc-at-Once recording (hereinafter referred to as DAO recording) will be described. The DAO recording implies sequential recording at a stroke without additionally recording data halfway from the Lead-in to the Lead-out, irrespective of the number of times of being data rewritable (for example, a DVD-R rewritable only once, a DVD-RW rewritable about 1000 times).
In contrast to the DAD recording, a recording method in which new data is sequentially recorded after the recorded data from the Lead-in to the Lead-out (or recorded continuously in a linking manner) is referred to as incremental recording. (In the incremental recording, seams are produced whereas in the DAD recording no seams are produced. The DAD recording points to a recording method and not whether or not the disc is rewritable.)
Of course, there are several conventional disc devices that start to record at a position other than the starting position of a basic recording area. One of them is, for example, the linking process that includes additionally recording new data after the recording data in the sequentially recording in a recording medium such as, for example, a DVD-R or DVD-RW. The linking process does not start to record at the exact starting point or at any position in the basic recording area, but to record at a specified position prescribed according to the disc standards.
There is another conventional recording device that starts to record not at a position that is prescribed according to the disc standards but at a position other than the starting position in the basic recording area in order to cope with a buffer underrun (JP-A-10-63433). When a quantity of data remaining in the buffer memory decreases below a prescribed quantity, the disc device itself stops its recording at a specified position beforehand set peculiarly in the basic recording area, and re-starts to record at the position where the recording stopped when the quantity of data remaining in the buffer memory is recovered.
At any rate, in the conventional device the start of the recording at the position other than the start position in the basic recording area is performed at a specified position, strictly speaking. Thus, when the recording stops at an unexpected position due to some external cause such as external vibrations/shocks, the device is not adapted to re-start the recording at the position where the recording stopped.
Also, in the incremental recording when the conventional device stops its recording at an unexpected position, it performed a repair process including apparently erasing the sequential recorded portion where the recording has stopped. Thus, the recording cannot re-start. In the linking process or in the process that cope with the buffer underrun, a useless area is needed on the recording medium for continuing the recording.
As described above, the conventional device need much time to return from a stoppage of the recording at an unexpected position in the disc-type recording medium which basically employs the sequential recording. This is especially a hindrance to application of a disc-type recording medium, which basically employs sequential recording, to a real-time recording system that records, for example, a video image on a real-time basis. Since in the real-time recording system information itself that is being recorded becomes an original source, re-recording the information from the beginning after the recorded information is erased, and exchange of the disc under use with a new one cannot be admitted even when the recording cannot help stopping due to some external cause. For such reasons, the real-time recording system using the conventional disc device is difficult to perform stabilized recording unless a randomly accessible recording medium such as DVD-R or DVD-RW is used. Thus, a disc-type recording medium such as DVD-R or DVD-RW that basically employ sequential recording is difficult to employ in the real-time recording system although it is inexpensive compared to the DVD-RAM.